HA & Disaster recovery are closely related, you obtain high availability upto 99.9% uptime by making sure that planned and unplanned downtime is kept to a minimum. Unplanned downtime can be reduced by architecting your system is protected against minor incidents.
HANA distributed system running on multiple hosts will guarantee the system will be up even if single node fails.
Disaster recovery takes a step further with a system designed it can handle a loss of complete datacenter.
What New in SPS 11 for HA +DR?
1. Continuous Log replay introduced
It is a commit based System replication, when a transaction commits on a primary node the log data will be shipped over and will commit on the secondary host. This reduces takeover time and network traffic.
2. Monitoring Secondary sites
Remote SQL access unpriotized to secondary site, schema is _SYS_SR_SITE_<SECONDARYDC>
3. HA DR provider
Automatically host or unhost certain tools (ex., vipMover )
4. Storage Snapshots as Replication source
When you initiate system replication you'll prompted for a backup, if none is available it has to be a regular snapshot used automatically.